Outdoor culture of Parasol Mushroom (Macrolepiota procera)

I found an single Parasol Mushroom growing in my yard so I figured I'd try to get it into cultivation. Location: Montreal Island, growing in the soil on the sunny, southern side of a hedge row (Arctic current). There's also the stump of an elm nearby, not quite dead but certainly with some decaying roots underground. So I have the mushroom cap and spore print, stem, and some mycelium from the base of the stem. I'm looking for suggestions about how to best propagate this in my yard. I have a variety of locations available from full sun to full shade, though I guess near where it was already growing would be a good bet? Also, what would be the best way to encourage the existing mycelium in the soil to expand?

solitary to widely scattered or in small groups in open woods and at their edges, in old pastures, along trails, etc; fairly common in the summer and fall in eastern North America (especially the New England and the south) and Mexico.

Although I donot have any personal experience growing the Parasol Mushroom, there is an excellent subchapter on how to grow them on pages 261-264 in "Mycelium Running", a book by paul stamets, complete with photos. Stamets has been successful with two methods.

Method one is to make a 4-inch deep bed of sawdust and woodchips in the early spring and then inoculate it with sawdust spawn at a rate of 5 pounds of spawn per 100 square feet. After the spawn has started growing, the bed should be overgrown with grass which is cut several times in a season. "Subsequent scatterings of woodchips are introduced in the late spring and midsummer. Placing this mushroom in moist, shallow, grassy depressions sloping toward watersheds with good exposure to sun encourages fruitings. Harnessing spores and stem butts for inoculation can greatly expand a few mushrooms into hundreds."

The second method is to inoculate thatch ant mounds (Formica species), which are a good natural habitat for this species. The nests become "infused with white mycelium within a few months of inoculation". The mounds will fruit a year or two later.

Nine years ago, when "Mycelium Running" was first published, I asked fungi perfecti if they were going to sell spawn of the Parasol Mushroom. They said they were still working on it before commercial release. To my knowledge they have never sold spawn of this species, apparently because of "liability concerns" over a toxic lookalike... Bummer!

If you have good mushroom-growing skills and experience with sterile culture, I recommend you try growing your own sawdust spawn from the spore print you have during the winter, then inoculate your bed(s) next spring with sawdust spawn. You can also spray spore slurry and plant stem butts around fresh wood chip/sawdust piles and ant mounds around your property right now. Good luck!!